1. Field of the Invention
The present invention basically comprises a lubricating additive which may be added to alcohol fuels to result in a stable alcohol fuel-lubricating additive solution for use as a fuel in internal combustion engines. Also disclosed and claimed are methods for preparing such fuel mixtures.
2. Description of the Prior Art
During the past decade we have witnessed a marked, worldwide increase in research and development efforts toward developing new fuel sources as alternatives to petroleum-derived fuels such as, for example, gasoline and diesel-oil. Perhaps the most popular and widely accepted fuel alternative available today, particularly in the United States, comprises a mixture of 90 percent gasoline and 10 percent ethanol sold as a fuel for internal combustion engines under the generic name "gasohol." While universal acceptance of gasohol as a fuel mixture would obviously result in a ten percent decrease in relative gasoline consumption, almost all researchers and economists agree that gasohol fuel is, at best, a stopgap solution to the petroleum dependence of both industrialized and developing nations. In similar fashion, almost all researchers and economists agree that a more satisfactory solution to this problem would be the development of a fuel source containing only very minor amounts such as, for example, significantly less than 10 percent of petroleum-derived ingredients.
Alcohols have been identified as the alternative fuel source having the greatest potential for use in both spark ignited and compression ignited engines. However, actual testing of alcohols such as ethanol and methanol as alternative fuels has revealed a substantial problem resulting from their use. Because such alcohol fuel compositions are substantially devoid of any petroleum derived products, they are notably deficient in lubricating properties with the result that engine wear from the use of these alcohol fuels in internal combustion engines will normally result in unacceptable premature failure of the engines. Moreover, similar wear problems occur not only in the engine, but also in fuel delivery and injection systems. Briefly stated, then, the primary difficulty with using alcohol fuels resides in efficiently and economically enhancing the lubricating properties of such fuels. While this problem is widely recognized and, therefore, relatively easy to state. the development of a truly efficacious solution to the problem has proved to be particularly elusive. Useful lubricants simply are not normally soluble in alcohol, and despite many years of research lubricating additives capable of forming stable solutions with alcohol in an efficient, economical manner simply have not been developed.
One prior art attempt at solving this problem is disclosed in U.S. Pat. No. 1,591,665 to Esselen. This patent recognizes that lubricating oil is not miscible with alcohol, and proposes the use of an alkali salt of a higher fatty acid as an emulsifier medium for maintaining the lubricating oil in intimate mixture, or blend, with the alcohol. While a blend certainly can be obtained in accord with the teaching of this patent, actual laboratory testing has shown that the blend simply is not stable. Over a relatively short period of time the lubricant simply separates from the alcohol resulting in the virtual elimination of any significant lubricating characteristics. Furthermore, this patent also recognizes the normal desirability of including another constituent such as ether as a significant portion of the fuel. Actual testing of the fuel of this invention has further revealed that lubricating oils of relatively low viscosity must be utilized in order to obtain the initial emulsion, and, obviously, such low viscosity oils would have significantly reduced lubricating characteristics.
U.S. Pat. No. 2,404,091 to Robertson teaches the use of a motor fuel comprising about 80-98 percent methanol and a minor proportion of a hydrocarbon of 3-5 carbon atoms. Other ingredients ordinarily used in motor fuels such as anti-knock agents may also be incorporated into the motor fuel of this invention. However, there is no disclosure of means for increasing the lubricating characteristics of the fuel. U.S. Pat. No. 2,789,891 to Brandes, et al., discloses a fuel system conditioner intended to be added to gasoline fuels. The disclosure of this patent is deemed pertinent as part of the prior art for the reason that the conditioner consists essentially of a homogeneous mixture of a light lubricating oil, an aliphatic alcohol, an aliphatic ketone and an ester of an aliphatic acid. However, this patent does not teach an alcohol fuel, per se; it merely discloses an additive for gasoline fuels.
U.S. Pat. No. 3,018,479 to Ilnyckyj, U.S. Pat. No. 3,567,639 to Aaron, and U.S. Pat. No. 3,693,720 to McDougall all disclose the use of ethylene-vinyl acetate copolymer in hydrocarbon oils as a pour point depressant and for the purpose of inhibiting deposition of wax on surfaces with which the oil may come into contact. However, none of these patents suggest that this copolymer might be effective in obtaining alcohol-lubricating oil fuel mixtures having stable solution characteristics.
Further searching of the prior art reveals numerous anti-wear compression ignition fuels for use in diesel engines assigned to Ethyl Corporation. Illustrative of these are the following U.S. Pat. Nos.:
4,177,768 PA1 4,185,594 PA1 4,198,931 PA1 4,204,481 PA1 4,208,190 PA1 4,242,099 PA1 4,248,182.
Unfortunately, as a review of this patent literature will confirm, there still is virtually no teaching of a lubricating additive mixture for alcohol fuels and fuel-additive mixtures suitable for use in spark ignited internal combustion engines which possesses sufficient lubricating properties to insure efficient operation of the engine.
Accordingly, it is clear that there is a great need in the art for lubricating additive mixtures suitable for use with alcohol fuels for the operation of internal combustion engines. It is to be understood that any such additive mixture must be capable of economic production. Perhaps even more importantly, however, the resulting fuel-additive mixture must comprise a stable solution for purposes of storage, transportation and ultimate end use.